In an organism, the brain directs the body how to respond to stimuli from the environment. In a cell, this function is performed by the-

The nucleus in eukaryotes and the cytoplasm in prokaryotes

Explanation:

The nucleus is the largest organ in a eukaryotic cell which is responsible for the control of the cell activities based on processing of received information and cell administration. The nucleus is therefore, known as the cell cell control center for regulating the metabolism of the cell and administers the cell and cellular information with which proteins are made

The nucleus contains nucleolus and it is the store for the chromosomes, which play an important role in genetics, related to the synthesis and replication of DNA and RNA

The functions of the nucleus are spread out through out the cytoplasm of prokaryotes.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).